1. Field of the Invention
The present embodiments relate to semiconductor wafer processing methods and equipment tools, and more particularly, to deposition of thin films used in sealing open pores of a porous dielectric material.
2. Description of the Related Art
Some semiconductor processing systems may employ plasma when depositing thin films on a substrate in a processing chamber. Generally, the substrate is arranged on a pedestal in the processing chamber. To create the thin film using chemical vapor deposition, one or more precursors are supplied by a showerhead to the processing chamber.
During processing, radio frequency (RF) power may be supplied to the showerhead or to an electrode to create plasma. For example, RF power may be supplied to the electrode embedded in a pedestal platen, which may be made of a non-conducting material such as ceramic. Another conducting portion of the pedestal may be connected to RF ground or another substantially different electrical potential.
When the electrode is excited by the RF power, RF fields are generated between the substrate and the showerhead to create plasma between the wafer and the showerhead. Plasma-enhanced chemical vapor deposition (PECVD) is a type of plasma deposition that is used to deposit thin films from a gas state (i.e., vapor) to a solid state on a substrate such as a wafer. PECVD systems convert a liquid precursor into a vapor precursor, which is delivered to a chamber. Such thin films can be deposited over various substrate materials, which may include previously etched features. Some materials, such as low-K (“K” being a dielectric constant) materials, may have a pore structure. The etched features, therefore, will produce open and exposed pores inside the features, e.g., feature walls.
Various methods exist to deposit thin films over the open, exposed pores inside features. Inevitably, the vapor precursors and atoms of the precursors used in such processing penetrate into the material through the largely interconnected pores altering their electrical properties. Such alteration may, for example, inadvertently increase the effective relative dielectric constant (i.e., the “K” value”) of the material. Unfortunately, even the solid thin film ends up penetrating into the underlying porous material instead of remaining close to the surface of the feature.
It is in this context that inventions arise.